This invention relates to a magnetic recording/reproducing apparatus for recording and reproducing information by making a magnetic tape travel by sending the tape from the supply-side reel and winding the tape on the take-up reel, and more particularly to a brake mechanism for applying a specified brake torque to the reel.
Generally, in a magnetic recording/reproducing apparatus using a magnetic tape as the magnetic recording medium, a relatively low-power brake is required which applies a back tension to the supply-side reel during tape travel to obtain a stable tape travel in addition to a powerful brake for stopping the two reels or one reel.
In this case, in a reel on the supply side during reproduction, the tension applied to the tape needs to be kept constant to achieve stable high-quality recording and reproduction. To this end, a tension control mechanism is provided which controls the tension variation within a small range by the use of a band brake and a tension arm. In a reel which serves as a supply side during reverse play, a stable travel of the tape is required. It is not necessary to control the tape tension unlike during playback, and therefore, a preload brake mechanism is provided which has the function of merely applying a brake torque to the reel.
Furthermore, it is also necessary to apply a back tension during high-speed reverse search in apparatuses of the type which are cable of high-speed reverse search to a reel serving as a supply-side reel during reverse play, in addition to the need to apply a back tension during reverse play. In this case, the back tension required during high-speed reverse search is smaller than the back tension required during reverse play. Therefore, in order to apply to the reel a desired one of multiple different back tensions with a single preload brake mechanism, a certain switching arrangement is required.
As a preload brake mechanism for applying two stages of brake torque to the reel, there is a technique disclosed in Published Unexamined Japanese Utility Model Application Sho No. 64-52136. This technique uses a mechanism for applying two stages of brake torque: a brake torque to fix one reel during tape loading and a brake torque during high-speed reverse search. Since this mechanism applies two stages of brake torque to the reel, this mechanism is applicable to a preload brake mechanism for applying two stages of brake torque during reverse play and high-speed reverse search.
However, in the technique of the above-mentioned Application model, there are provided two elastic members for applying an urging force to the brake lever and a rotary lever for switching the urging force in addition to a brake lever for applying a brake torque to the reel. The use of two elastic members limits the freedom of arrangement of the members, and requires a wide installation space, thus greatly reducing the degree of freedom of design. This makes the whole apparatus arrangement large and complicated. Moreover, in the technique of the above-mentioned Application, it is possible to switch the brake torque in two stages, but it is not possible to switch the brake torque in three or more stages. The technique of the above-mentioned Application cannot apply three different stages of brake torque to the reel in correspondence to reverse play and high-speed reverse search and stopping the reel.
As described above, in a brake mechanism used in a conventional magnetic recording/reproducing apparatus, there has been the drawback that it is impossible to switch the brake torque in three or more stages. Another drawback is that the use of two elastic members reduces the degree of freedom of design, resulting in a large and complicated arrangement of the whole apparatus.